Proteins

Question 1

What are proteins important for?

Answer 1

-enzymes-antibiotics-haemoglobin-hormones eg insulin-receptors and channels-structure (muscles)-cytoskeleton -keratin (hair and nails)

Question 2

What are polymers made out of?

Answer 2

Monomers called amino acids.

Question 3

How many amino acids are there?

Answer 3

20 in total

Question 4

What are amino acids made of?

Answer 4

C,H,O,N and sometimes S

Question 5

How are amino acids joined?

Answer 5

By peptide bonds

Question 6

Two amino acids joined are called…

Answer 6

Dipeptide

Question 7

More than two amino acids joined are called…

Answer 7

polypeptide

Question 8

One or more polypeptides are called…

Answer 8

A protein

Question 9

What varies about the structure of the amino acids?

Answer 9

Have the same basic structure but have a variable R group.

Question 10

What is the structure of a basic amino acid?

Answer 10

See Notes

Question 11

How are dipeptides and polypeptides formed and broken down?

Answer 11

Formed by condensation reactions and broken down by hydrolysis reactions.

Question 12

How many levels are there in protein structure?

Answer 12

4

Question 13

Do all proteins have all 4 structures?

Answer 13

They all have the first 3 and only some have the fourth.

Question 14

What are the 4 structures?

Answer 14

-Primary Structure-Secondary Structure-Tertiary Structure-Quaternary Structure

Question 15

What is the Primary Structure?

Answer 15

The sequence of amino acids that make up the polypeptide chain.

Question 16

In the Primary Structure, what could happen if an amino acid changed?

Answer 16

Could affect the whole protein.

Question 17

What is the Secondary Structure?

Answer 17

Where the polypeptide chain folds into an alpha helix or a beta pleated sheet

Question 18

Why does this folding happen in the Secondary Structure?

Answer 18

Because the -NH and the -CO groups are polar so hydrogen bonds form between them.

Question 19

What is the Tertiary Structure?

Answer 19

Where the alpha helix or beta pleated sheet folds further due to additional bonding between nearby R-groups.

Question 20

What are the 4 type of bonds in the tertiary structure?

Answer 20

-Disulphide Bridge
-Ionic Bonds
-Hydrogen Bonds
-Hydrophobic /Hydrophilic interactions

Question 21

Where are the Disulphide bridge bonds in the tertiary structure?

Answer 21

Between sulphur atoms in nearby cytosines.

Question 22

Where are the Ionic bonds in the tertiary structure?

Answer 22

Between - and + R groups.

Question 23

Where are the Hydrogen bonds in the tertiary structure?

Answer 23

Between S+ hydrogens and S- atoms in nearby R groups.

Question 24

Where are the Hydrophilic/Hydrophobic interactions the tertiary structure?

Answer 24

Hydrophobic R groups-insideHydrophilic R groups-outside

Question 25

What is the Quaternary Structure?

Answer 25

Where several polypeptide chains join together.

Question 26

How are these several polypeptide chains held together in the quaternary structure?

Answer 26

Held together by the same bonds found in the tertiary structure.

Question 27

What are the 2 types of protiens?

Answer 27

Globular and Fibrous

Question 28

What is the structure of Globular Proteins and how is this formed?

Answer 28

Round, Compact structure due to hydrophobic and hydrophilic interactions

Question 29

Why are Globular Proteins Soluble?

Answer 29

The hydrophilic parts are on the outside so they're easily transported in fluid.

Question 30

What are the 3 examples of Globular Proteins?

Answer 30

-Amylase -Insulin -Haemoglobin

Question 31

What is Amylase made from? And what does it beak down into?

Answer 31

A single polypeptide chain and breaks down into maltose.

Question 32

What does the secondary structure of Amylase consist of?

Answer 32

Alpha helix and beta pleated sheets which then fold up into a Globular Protein.

Question 33

What is Insulin?

Answer 33

Produced by the pancreas and helps to regulate blood-glucose levels.

Question 34

What is Insulin made from?

Answer 34

2 polypeptide chains (a dimer) held together by two disulphide.

Question 35

What is Insulin stored as?

Answer 35

A hexamer (a globular protein) due to hydrophobic/hydrophilic interactions between the dimers.

Question 36

What is Haemoglobin made out of?

Answer 36

4 polypeptide chains-2 alpha chains and 2 beta chains (in adults). Each chain is globular.

Question 37

What type of proteins are the polypeptides made from?

Answer 37

Conjugated proteins.

Question 38

What are conjugated Proteins?

Answer 38

Proteins with a prosthetic (non-protein) group attached to them.

Question 39

How many prosthetic groups does haemoglobin have and what is its name?

Answer 39

4 prosthetic groups called haem.

Question 40

What do each of the prosthetic groups contain?

Answer 40

One iron atom which can bind to one molecule of O2.

Question 41

What is the structure and characteristics of Fibrous Proteins?

Answer 41

-Structural Proteins -Long, strong, tough and rope shaped. -Insoluble, non-polar and unreactive.

Question 42

What are 3 examples of Fibrous Proteins?

Answer 42

-Collagen -Keratin -Elastin

Question 43

What is Collagen?

Answer 43

A very strong protein fibril which is flexible but doesn't stretch.

Question 44

Where is Collagen found?

Answer 44

Skin, bone, blood vesicles, muscles, ligaments, tendons and cartilage.

Question 45

What is Collagen made out of and what structure is it in?

Answer 45

3 polypeptide chains arranged in a triple helix, held together by hydrogen bonds.

Question 46

Where is Keratin found?

Answer 46

In the external structure of many animals.

Question 47

What are the 2 characteristics of Keratin?

Answer 47

Can be tough or flexible

Question 48

Where is Elastin found?

Answer 48

Connective tissue of the skin, lungs, bladder, arteries and some ligaments

Question 49

How do you test for a protein?

Answer 49

1)Add some sodium hydroxide solution and shake. 2)Then add some dilute copper sulphate solution. 3)If pale blue colour turns purple there is a protein present.

Question 50

What are we really testing for when we test for a protein?

Answer 50

The peptide bond

Question 51

What could be used instead of using sodium hydroxide and then dilute copper sulphate?

Answer 51

Biurets as they contain both of these.